Measurement of sodium intake and its relationship to blood pressure and salivary sodium concentration

The mean daily sodium intake was determined for 33 normotensive subjects by analysis of a 7 day 24 h urine collection. The intake range was 1.75–5.77 g Na/day with an intra-individual standard deviation of 1.08 g Na and an inter-individual standard deviation of 0.80 g Na giving a ratio of intra-to inter-individual variance of 1.82, 79% of the subjects were correctly classified into the approapriate tertile for sodium intake after the 7 day collection. The intake range for potassium was 1.54 to 4.2 g/day.No relationship was observed between blood pressure and sodium or potassium intake. Salivary sodium levels (both stimulated and unstimulated) were positiviely correlated with sodium excretion of the day preceding saliva collection.